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              LABS, INC.                        Brookings, SD 57006           www.SoDakLabs.com
                                                                                                                    www.SoDakLabs.com
             Grass Seed Testing Services
             GRASS GERMINATION                                                WHAT IS REPORTED 
             METHODS                                                          Pure seed, inert matter and other seed percentages by 
             Testing is conducted according to the Association Official       weight.  For AOSA Rules other seeds are reported as 
             Seed Analysts (AOSA), International Seed Testing                 other crop seed and common weed seeds per Handbook 
             Association (ISTA) Rules for Testing seeds or Canada             29 classification.
             Methods and Procedures (Canada M&P) based on                     Noxious weeds seeds in specific state(s) or the entire 
             customer need.  Each germination test consists of four           lower 48 states are reported.
             hundred randomly selected pure seeds.  Media utilized is 
             top of paper (TP) and duration is dependent upon species.        VALUE OF RESULTS 
             WHAT IS REPORTED                                                 Purity and noxious results are required on the seed bag 
             Percentages of normal seedlings, abnormal seedlings, and         label.
             dead seeds.  Abnormalities and fungal species present are        GRASS TETRAZOLIUM TEST 
             reported in comments.                                            METHODS 
             VALUE OF RESULTS                                                 Tetrazolium tests are conducted on a 200 seed sample.  
             The standard germination test is required by the Federal         Seeds are typically imbibed for 16 hours and bisected 
             Seed Act (FSA) for labeling.  The report of analysis will        through the embryo or pierced then soaked in 0.1% or 1% 
             contain germination percentage and date of test utilized         tetrazolium solution.
             for labeling.                                                    WHAT IS REPORTED 
             GRASS PURITY & NOXIOUS                                           A percentage of viable seed (normal staining embryos 
             WEED EXAMINATIONS                                                and any dormant seeds).
             METHODS                                                          VALUE OF RESULTS 
             Purity and Noxious weed seed examination or Other Seed           Tetrazolium is a quick estimate of germination and can be 
             determination can be conducted using the Association             useful in determining viability of hard seeds.
             Official Seed Analysts (AOSA) Rules for Testing Seed or 
             International Seed Testing Association (ISTA) testing 
             methods.  Samples are physically examined for inert, 
             weed and crop seeds.
               FIGURE 1.  Big bluestem germination        FIGURE 2.  Noxious weed                   FIGURE 3. Cross section of 
               after 14 days on blue blotters, note       examination to detect weeds in            Beardless Wildrye seed showing the 
               saprophytic fungal development on seed     noxoious in lower 48 states of North      layers within the seed coat.
               seed units.                                America.
                 TABLE 1. Comparison of Native Grass Testing methods on three species and two to four different testing methods.
                                               Prechill      Germ.                                                  Viability of firm,                  Statement on Report  
                    Species/Method              (days)       (days)          Dormancy Breaking                ungerminated at conclusion                     of Analysis
                                                                                                                    of 400 seed germ
                    SWITCHGRASS
                      AOSA Table 6A               14           14       PC, Light, Alt Temp, KNO3           TZ at 28th day of firm               “In accordance with AOSA 
                                                                                                            remaining                            Rules”
                      AOSA Table 6A                0           14       Light, Alt Temps, KNO3              TZ at 14th day of firm               “In accordance with AOSA 
                                                                                                            remaining                            Rules”
                      AOSA 6.9p                    0           14       Light, Alt Temps                    TZ at 14th day of firm               “14 day germ test conducted 
                                                                                                            remaining                            using no dormancy breaking 
                                                                                                                                                 methods”
                      NOT AOSA                     0           14       Light, Alt Temps, KNO3              NA/ separate 200 seed TZ             “Germination test was not 
                      (Section 15.m)                                    and/or GA3 or other.                used and TZ% minus 14 day  conducted in accordance 
                                                                                                            germ% = Dormant %                    with AOSA Rules”
                    BIG BLUESTEM
                      AOSA 6A & 6.9p               0           14       Light/Alt Temps                     TZ at 14th day of firm               “In accordance or no 
                                                                                                            remaining                            dormancy breaking”
                      NOT AOSA                     0           14       Light, Alt Temps, KNO3              NA/ separate 200 seed TZ             “Germination test was not 
                      (Section 15.m)                                    and/or GA3  or other.               used and TZ% minus 14 day  conducted in accordance 
                                                                                                            germ% = Dormant %                    with AOSA Rules”
                    LITTLE BLUESTEM
                      AOSA 6A & 6.9p               0           14       Light/Alt Temps                     TZ at 14th day of firm               “In accordance or no 
                                                                                                            remaining                            dormancy breaking”
                      NOT AOSA                     0           14       Light, Alt Temps, KNO3              NA/ separate 200 seed TZ             “Germination test was not 
                      (Section 15.m)                                    and/or GA3 or other.                used and TZ% minus 14 day  conducted in accordance 
                                                                                                            germ% = Dormant %                    with AOSA Rules”
                 Species Sold on a Pure Live Seed (PLS) Basis: Hundreds                                components of test methods and the actual test methods.  
                 of species are sold on a PLS basis, many are considered                               In Table 1. Three species are compared, Switchgrass with 
                 native species.  PLS is calculated as % Pure Seed x %                                 four different test methods and Big and Little bluestem 
                 Total Viable (Germ + Dormant) = PLS %.   How these PLS                                with two test methods, respectively.  Three official 
                 valued species are tested  can have a significant monetary                            methods exist for Switchgrass, two with dormancy 
                 influence of the value of a seed lot.  Reducing variation                             breaking (prechilling and KNO ) and one with no 
                 within the AOSA Rules for Testing Seeds methods and/or                                                                           3
                                                                                                       dormancy breaking and all three having “post-germ 
                 having the respective laboratories report their methods,                              TZ” to determine dormant seed percentage.  The fourth 
                 can help explain some of variation  in PLS % seen from                                method used by a few laboratories, combines the results 
                 different laboratories on the same seed lot.                                          of a 200 seed “pre-germ TZ” test and a four hundred 
                 Annually, testing methods change within the AOSA                                      seed germination tests to arrive at total viable seed 
                 Rules.  In the late 1980’s, the AOSA Rangegrass                                       percentages.  Though this method is not in accordance 
                 Committee submitted proposals which reduced the                                       with the AOSA Rules (section 15.m of the AOSA Rules 
                 length of testing for 28–60 days to 14–28 days for many                               requires use of a statement to that fact on the report of 
                 native grasses.  The lengthy tests time frames had existed                            analysis),  it does remove the source of variation due to 
                 prior to the use of Tetrazolium (TZ) testing to determine                             pure seed determination.  Since the analyst must cut 
                 the viability of firm ungerminated seeds.   Prior to TZ,                              pure seed units submitted for the pre-germ TZ, as they 
                 analysts often prolonged tests hoping for germination                                 are preparing seeds for TZ staining, they can remove 
                 and often the dormant seeds became colonized by                                       any inert seed units from consideration of viability.  If 
                 saprophytic fungi leading to loss of viability.  Shortening                           inert pure seed units are submitted to a germination test 
                 test length and adopting section 6.9p “No Dormancy                                    with a “post-germ TZ” method, those inert units often 
                 Breaking Treatments” within the AOSA Rules has                                        appear as “not firm seeds” at completion of the test and 
                 reduced variability in PLS determinations.  However,                                  are considered nonviable and can result in a lower total 
                 variation still exists due to pure seed determination,                                viable seed percentage.